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A New Twist on “You Are What You Eat”?

In a previous post, I alerted readers about research from China’s Nanjing University reporting that small bits of genetic material from ingested plants may regulate gene expression in mice.

These surprising results from Chen-Yu Zhang’s lab claimed that bits of plant genetic material called microRNAs could actually make it intact from the animals’ digestive systems into their bloodstreams and turn off some of the animals’ own genes.

Nope

A new research paper from The Johns Hopkins School of Medicine refutes these claims, reporting “…that Zhang’s results were likely a false positive that resulted from the technique his group used. The new study, the Johns Hopkins group says, bolsters the case of skeptics who argued that genetic material from food would have little chance of surviving the digestive system, much less crossing the intestinal lining to enter the bloodstream.” (from Johns Hopkins news release)

Though he clearly showed how the Zhang lab may have been fooled by “false positives”, the lead author of the Johns Hopkins paper (see Ref. 1 below) said that it’s possible that very low levels of plant microRNAs could enter the bloodstream. He cautioned, however, that even if this happened, it’s unlikely that such small numbers of molecules could significantly affect gene expression.

It’s clear that more research will be needed to determine whether low-level transfer of ingested plant microRNA’s actually occurs, and, if so, how this may affect gene expression in animals.

Reference

1. Witwer, K. W., M. A. McAlexander, S. E. Queen, and R. J. Adams (2013) “Real-time quantitative PCR and droplet digital PCR for plant miRNAs in mammalian blood provide little evidence for general uptake of dietary miRNAs: Limited evidence for general uptake of dietary plant xenomiRs.” RNA Biology, Vol. 10, pp. 0-6 (online). (Abstract)

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